Seven people in two cars on the Highway M overpass in Scott County were injured, none seriously, when two 40-foot sections of the overpass crumpled. All seven had been released from an area hospital Saturday.

‘‘The damage is very extensive,’’ Mark Shelton, engineer for the Missouri Department of Transportation’s southeast region, said Sunday. ‘‘We’re going to end up removing the entire bridge and completely replacing it.’’

Shelton said the overpass replacement is estimated to cost about $3 million, and the bridge is expected to reopen in early September.

The overpass, which was built about 15 years ago, is used by about 400 to 500 cars a day, mostly between Chaffee, Scott City, and Cape Girardeau. The National Transportation Safety Board said the bridge was given rated ‘‘good’’ after its last inspection in February.